This invention relates to structures, and more particularly, to a pressure regulated structure.
Tanks containing cryogenic liquids for space applications often have a skin composed of a composite material because of its superior combination of weight and strength characteristics versus metal. Unfortunately, cryogenic liquids, such as, for example, liquid hydrogen, liquid oxygen, and liquid helium, have a tendency to penetrate composite materials and convert, possibly when heated, to a gaseous form. Thus, if such a tank is heated, the gas in the skin readily expands, possibly causing the tank""s skin to destruct.
The present invention substantially reduces and/or eliminates at least some of the problems and disadvantages associated with previously developed fluid containment systems. Accordingly, the present invention provides, at least in particular embodiments, a pressure regulated structure that is useful in fluid containment systems.
In certain embodiments, a pressure regulated structure includes a first layer, a second layer, a non-metallic honeycomb assembly, and a vent. The non-metallic honeycomb assembly is between the first layer and the second layer and includes a plurality of walls forming cells, at least some of the walls including laser-formed apertures to allow fluid communication between cells. The vent is fluidly coupled to the honeycomb assembly, wherein fluid in the cells of the honeycomb assembly may be removed through the vent to decrease pressure in the structure.
In particular embodiments, a method for manufacturing a pressure regulated structure includes lasering apertures in at least some of the cell walls of a non-metallic honeycomb assembly to allow fluid communication between cells. The method also includes coupling the assembly to a first layer and coupling the assembly to a second layer, wherein fluid in the cells of the honeycomb assembly may flow between cells to be removed from the structure.
The present invention possesses several technical features. For example, by including apertures in the honeycomb assembly, fluid that penetrates the structure may be removed. Thus, the structure, and a system of which it may be a part, may be protected from pressure build-up due to internal and/or external fluid penetration. As another example, by forming the honeycomb assembly of a non-metallic material, the structure, and a system of which it may be a part, may have enhanced insulative characteristics. As a further example, by using a laser to form the apertures in the cell walls of the honeycomb assembly, the aperture sizes and locations may be tightly controlled, and, if needed, the sizes of the apertures may be made relatively small. Thus, the impact of the apertures on the integrity of the honeycomb assembly may be predicted with reasonable accuracy and may be made relatively small. Moreover, the apertures may be formed using minimal physical contact with the honeycomb assembly, which helps to reduce damage thereto. As an additional example, in embodiments where the apertures are formed primarily or exclusively in the non-ribbon walls of the cells, better structural performance may result for the honeycomb assembly.